Chill member



April 1940- M. G. STERNBERG ,197,025

CHILL MEMBER Filed April 17, 1937 Patented Apr. 16,1940

CHILL MEMBER Matthew-G. Sternberg; East Chicago,- bid, as:

signor to Continental Roll & Steel Foundry Company, EastGhic-ago, Ind a corporation of Delaware Application April l'i, 1937, Serial No. 137,453 I 2 Claims. (0122-174) The present invention relates to chill members for use in casting large steel and alloy rolls for rolling mills and methods of casting such rollst In connection with the manufacture of rolls 5 for rolling mills and particularly rolls of rela tively large sizes, that is to say, rolls from 30 inches in diameter and larger, a greatdeal of difficulty has been experienced in the past from r011 breakage resulting from internal stresses and strains within the metal comprising the body of the roll.

It was formerly believed that this breakage was due to improper annealing. Thereason the-annealing was believed to be at fault was because at the point of breakage the outer layer of'metal constituting the roll appeared to have a fine grain structure whereas themetal as it approached the center of the roll would have a coarse grain structure and it was thought that the annealing had merely penetrated a short distance and that the interior of the roll was improperly annealed. Various attempts have been made in the past to overcome breakage. It has even been suggested that large rolls be formed by making an arbor and sweating a sleeve onto, the arbor and thus, in view of the reduced masses of metal to be cast at one time, to eliminate: internal stresses'and strains. I i.

I have discovered, however, that in the majority .of cases the internal stresses and strains in the roll which cause breakage are not due to faulty annealing but rather to'ithe fact that in I casting large rolls it is necessary that the metal be poured at. relatively-low temperatures and after the metal is poured due to the unevencooling there is set up an internal strain located in the interior thereof which causes the roll to break v under rolling stresses. The strains may be so great that there is a crack or fissure formed in the interior of the roll that extends at approximately right angles to the axis thereof. In some cases where the roll breakages are due to defects in the casting of the roll, it is possible. to measure the extent of this crack.

The fault is not due to the annealing. It will be found that although the fracture shows a circular band of sound metal at the periphery of the roll and the central area hasa different type of structure varying from coarse to very coarse or of the concrete type that if a section is cut directly beneath the fracture the grain structure will vary but slightly and is practically uniform throughout theentire cross section of the roll.

I have discovered that the stresses and strains which cause breakage are due to improper cool- ,dotted lines and designated as E.

inated by the use of an internal cooling medium;

To illustrate my invention in moredetail, there is shown in the'accompany drawing a diagram* matic view of a roll illustrating the manner in which the cooling ordinarily takes place'and in the remaining viewsis shown a preferred form of internal cooling member. It is to be understood, however, that the drawing and the accompany-'- ing specification are for purposes 'of exemplification only and. that modifications may be madeiri the" form of cooling medium'used audits method of application without departing from the'spirit and scope of theinvention defined in the appended claims. In the drawing: 1 a

Fig. l is a sectional view showing the stages of solidification of a-. roll as it cools after being poured; Fig. 2 is a View in elevation showing a pref ierredform'of internal cooling member; and Fig. 3 is a'section taken on the line '35-3 of Fig.2.. 1

Referring toFig. i a the drawing, it Will be 1 observedthat'the roll is divided" into zoneswhich have beenidentified' by the "letters A', B, C and D, respectively.- In-the ordinary coolingof a-roll the zone identified *by. theletter A cools and solidifies first, the metal in the zones B, C and vD being still at a high temperature and in an expanded condition after zone A'has solidified.

PATENT OFFICE: I j

' ing of the roll after being cast and may be elim- The metal i n zone B then solidifies while'the metal in zones C and D isstill in an expandedand fluid condition. "Zone C'next solidifies and leaves the final zone D in an expanded fiuid condition. As zone D cools, and solidifies it also contracts and since the surrounding zones are in solid condition the weight of the metal in zone D tends to I pull the top portion of this metal away from zone C as the metal cools at the point indicated in It is when the metal reaches a mushy stage that its weight tends to cause such separation to take place thus resulting in a fault or strain in the roll body.

The zones illustrated in Fig. l of the drawing are purely illustrative as the zonesv .will vary with difierent sizes and shapes of rolls but it will be found'in'generalthat in a plane body roll the last portion to 0001 will be in the upper central portion of the roll body and that the strain will take place at this point.

In Figs. 2 and 3 of the drawing I have shown a preferred form of internal cooling member which, when properly applied, will avoid the setting up of internal strains which tend to weaken the roll and which result in its failure. This member comprises a central steel support H arms is which may be welded or otherwise at tached to the supporting member I I and thebars |2. Similarly, the long bars I3 are attached to' the member I l by supporting arms IS.

The upper end of the supporting member i l-' provided with cross members 16 which arev adapted to engage the upper edges of the mold in which the roll is being cast-and thus prohibit the cooling member from dropping into the metal beyond the desired point. A ring'rmem'ber H is provided at the top of the cooling member so that it may be readily handled by a crane. I

It will be observed that the short bars H are not in position parallel with the member H but converge toward their upper end and the long bars I3 converge toward their lower end. As shown in the drawing the inner ends of these bars I? and I3 may overlap or be interposed between each other. The inner ends of the two sets of bars are so located as to be in the upper half of the body of the roll when it is cast. The object in so arranging the bars is'to have them so positioned that they will be most efiectivein the distribution of heat in that portion of the roll which would normally solidify last, namely, in the zones C and'D and particularly D, as. illustrated in Fig. 1 because. of the formation of more columns of metal at that. point by means of the overlapped bars. Of course, with a change in the shape of the roll body it would be necessary to change the general arrangement and size of the bars around the supporting member H. a

In the use of this internal cooling medium when casting a large roll for rolling mills I have found that in order for it to be. most effective it must be inserted into the cast metal a period of time after the metal has been poured. If themember is placed in the metal too soon it. melts and is not effective in the elimination of the strain conditions which it is intended toovercome. It is desirable, however, that the member be inserted in the metal sufiiciently soon after pouring so that it fuses.

When the internal cooling memberv is inserted in the roll the central supporting member and the outside bars cool-the'metal immediately adjacent to them and form within the, roll a plurality of columns, of metal which have some strength and thus as the roll cools there is no extensive fluid portion which finally cools as a i segregated whole. metal built up within the roll body tend to hold the metal together and prohibit it from separat ing and causing a fault or a strain.

Furthermore, the columns or The time of insertion is of importance in order to accomplish this result and while some variation in time is permissible," arulewhich may be generally followed is that with a thirty, inch di ameter plane body roll the cooling member should be inserted at the end of thirty minutes after the metal has been poured and foreach inch the r I diameter of the roll increases there should beone additional minute delay before inserting the cool ing member; that: is. to say, it should be inserted after forty minutes in a forty inch diameter roll, 1 etc. v j When this type of cooling member is used in rolls having a shaped body, such as rolls used in rolling rails, beams and the like,'the time of insertion will vary somewhat from that of a plane i I body roll "depending upon theshape of theroll.

In connection, withsuch. rolls. the general rule, is.

that the member should be inserteda sufiicient time after casting so as, not to be completely'absorbed anda short time prior to of the interior of the roll.

I have found thatby the use of internal cooling medium of the type herein describedand. set forth that internal strains and stresses due to the casting of large rolls for rolling mills are eliminated for all practical purposes and, there fore, breakage from this cause is reduced to a minimum. a v

I claim:

1. A chill memberfor use in casting large size solidification ity' of bars surrounding and supported by said member adjacent its lower end, both groups 'ofbars running generally longitudinally of said sup porting member and converging from the inner ends of said bars towards the outer ends of said supporting member, the 'ba-rs of the first named roup being interp sed between the bars of the a second named groupat. their inner ends.

2. A chill member as described in claim. 1' and wherein the bars of. the first named group are shorter than the bars of the second named group.

MAT HEW G. S'IERNBERG. 

